UNIVERSITY   OF   CALIFORNIA 

COLLEGE   OF   AGRICULTURE 

AGRICULTURAL    EXPERIMENT   STATION 

BERKELEY,    CALIFORNIA 


Reclamation  of  the  Fresno  Type 
of  Black-Alkali  Soil 

W.  P.  KELLEY  and  E.  E.  THOMAS 


BULLETIN  455 

June,  1928 


UNIVERSITY   OF   CALIFORNIA   PRINTING   OFFICE 

BERKELEY,  CALIFORNIA 

1928 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/reclamationoffre455kell 


FOREWORD 

It  has  been  known  for  many  years  that  the  excess  of  alkali  in  some 
of  the  soils  of  California  constitutes  an  important  agricultural  prob- 
lem. The  late  Dr.  Eugene  W.  Ililgard,  for  many  years  (1875  to  1905) 
Professor  of  Agriculture  and  Director  of  the  California  Agricultural 
Experiment  Station,  prosecuted  extensive  studies  on  alkali  soils  and 
added  greatly  to  our  knowledge  and  understanding  of  them.  He  was 
a  pioneer  in  this  field  of  research  and  his  investigations  were  classical 
for  their  time.  However,  much  remained  to  be  determined  as  regards 
a  thorough  understanding  both  of  the  fundamental  nature  of  alkali 
soils  and  of  the  best  practical  methods  of  reclamation. 

The  rapid  extension  of  irrigated  agriculture  has  caused  the  alkali 
problem  to  become  more  acute  in  various  places.  The  importance 
of  this  phase  of  the  question  has  made  it  imperative  to  conduct  further 
investigations.  The  Kearney  Vineyard,  owned  by  the  University  of 
California,  experienced  considerable  damage  from  the  rise  of  the 
water  table  and  the  accumulation  of  alkali  on  or  near  the  surface  of 
the  soil.     Experiments  were  therefore  undertaken  there. 

Several  years  ago  an  attempt  was  made  to  reclaim  a  quarter 
section  of  this  soil  by  tile  drainage  and  flooding,  but  the  results  were 
only  partially  successful.  It  became  evident  that  further  investi- 
gation of  the  fundamental  aspects  of  the  alkali  problem  was  needed. 
Accordingly  a  detailed  laboratory  study  and  an  extensive  series  of 
field  experiments  were  begun  in  1919  by  the  College  of  Agriculture 
and  placed  under  the  direction  of  Dr.  W.  P.  Kelley,  Professor  of 
Agricultural  Chemistry  in  the  Citrus  Experiment  Station.  The 
present  bulletin  by  W.  P.  Kelley  and  E.  E.  Thomas  presents  the  first 
popular  report  of  these  field  experiments.  In  addition  to  the  papers 
listed  in  "Literature  Cited"  (p.  37),  the  following  technical  papers 
have  already  been  published  on  this  work  or  are  in  the  course  of 
preparation : 

1.  Kelley,  W.  P.,  and  A.  B.  Cummins. 

1921.  Chemical  effect  of  salts  on  soils.     Soil  Sci.  11:139-159. 

2.  Kelley,  W.  P. 

1922.  Variability  of  alkali  soil.     Soil  Sci.  14:177-189. 

3.  Cummins,  A.  B.,  and  W.  P.  Kelley. 

1923.  The    formation   of    sodium    carbonate   in    soils.      California    Agr. 

Exp.  Sta.  Tech.  Paper  3:1-35. 

4.  Kelley,  W.  P.,  and  S.  M.  Brown. 

1924.  Eeplaceable  bases  in  soils.     California  Agr.  Exp.  Sta.  Tech.  Paper 

15:1-39. 


5.  Kelley,  W.  P.,  and  S.  M.  Brown. 

1925.     Base  exchange  in  relation  to  alkali  soils.     Soil  Sci.  20:477-495. 

6.  Cummins,  A.  B. 

[1926.]  The  solubility  relationships  of  calcium  carbonate  with  special 
reference  to  the  formation  of  sodium  carbonate  in  soils.  Un- 
published thesis  submitted  in  1926. 

As  a  result  of  these  investigations  and  similar  studies  made  in 
Europe,  some  of  the  more  puzzling  phases  of  the  alkali  problem  have 
already  been  elucidated.  Probably  the  most  important  point  that  has 
come  out  of  these  technical  studies  is  the  thorough  establishment  of 
the  fact  that  alkali  soils  can  no  longer  be  regarded  as  soils  which 
merely  contain  an  excess  of  soluble  salts.  The  soluble  salts  upon 
accumulation  react  with  the  clay  constituents  of  the  soil,  thus  chang- 
ing their  fundamental  chemical  nature  and  the  changes  thus  wrought 
must  be  overcome  in  the  treatment  of  the  soil  before  it  can  be  said 
to  be  reclaimed. 

These  and  other  investigations  are  being  continued,  and  further 
papers  will  be  issued  as  the  work  progresses. 

H.  J.  Webber, 

Director,  Citrus  Experiment  Station. 


RECLAMATION    OF   THE    FRESNO   TYPE    OF 
BLACK-ALKALI    SOIL1 

W.  P.  KELLEY-  and  E.  E.  THOMASa 


INTRODUCTION 

This  bulletin  reports  the  results  of  a  series  of  alkali-reclamation 
experiments  that  have  been  made  at  Kearney  Park,  near  Fresno, 
California. 

Within  a  few  years  after  irrigated  agriculture  was  introduced 
into  the  section  southwest  of  Fresno,  the  water  table  began  to  rise  as 
a  result  of  seepage  and  excessive  irrigation.  This  caused  the  soluble 
salts  that  were  present  in  the  deeper  subsoil  layers  to  move  upward 
by  capillarity  and  finally  to  accumulate  on  or  near  the  surface  of  the 
soil.  The  consequence  has  been  that  a  comparatively  large  area  of 
formerly  alkali-free,  productive  soil  has  become  severely  affected  with 
alkali.  A  similar  condition  has  developed  in  other  parts  of  the  San 
Joaquin  Valley.  The  soil  conditions  of  these  areas  closely  resemble 
those  of  a  much  larger  area  still  further  south  and  west  of  Fresno, 
where  an  excess  of  soluble  salts  has  accumulated  as  a  result  of  purely 
natural  causes. 

An  attempt  was  made  in  1914  and  1915 (4)  to  reclaim  a  quarter 
section  (160  acres)  of  alkali  soil  on  the  Kearney  Vineyard  by  means 
of  tile  drainage  and  flooding.  The  experiment  was  only  partially 
successful.  Comparatively  large  spots  scattered  here  and  there  over 
the  drained  area  remained  unproductive,  and  in  1919  a  large  part 
of  this  quarter  section  failed  to  produce  a  profitable  crop  of  barley. 

The  soluble  salts  of  this  soil  consist  chiefly  of  the  carbonate, 
bicarbonate,  chlorid,  and  sulfate  of  sodium.  Special  investigations 
have  shown  that  as  the  soluble  salts  accumulated  in  the  soil,  the 
sodium  reacted  with  and  consequently  altered  the  chemical  nature 
of  an  important  component  of  the  clay  constituents  of  the  soil.  We 
now  know  that  this  change  is  more  important  chemically  and  much 
more  difficult  to  overcome  practically  than  the  excess  of  soluble  salts. 


i  Paper  No.  183,  University  of  California,  Graduate  School  of  Tropical  Agri- 
culture and   Citrus   Experiment   Station,   Riverside,   California. 

-Professor  of  Agricultural  Chemistry  in  the  Citrus  Experiment  Station  and 
Graduate  School  of  Tropical  Agriculture  and  Agricultural  Chemist  in  the  Experi 
ment  Station. 

3  Assistant  chemist  in  the  Experiment  Station. 


6  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Ordinary  leaching  does  not  bring  about  the  needed  changes  in  these 
constituents.  It  is  partly  because  of  this  fact  that  the  previous  drain- 
age and  flooding  experiment  failed  to  produce  satisfactory  results. 

The  proper  objective  in  the  treatment  of  this  soil,  and  the  same 
is  true  of  black-alkali  soils  in  general,  is,  therefore,  not  merely  to 
remove  the  excess  of  soluble  salts,  but  also  to  convert  the  clay  con- 
stituents back  into  the  state  that  existed  before  the  excess  of  soluble 
salts  accumulated  in  the  soil.  In  normal  soils  these  constituents  are 
predominantly  calcium  compounds,  whereas  in  the  Fresno  alkali  soil 
they  have  been  partially  converted  into  sodium  compounds  through 
the  action  of  soluble  salts. 

In  order  to  remove  the  soluble  salts  and  to  prevent  their  return 
into  the  soil  by  capillarity,  the  water  table  must  be  kept  down  perma- 
nently. It  now  seems  certain  that  unless  the  water  table  is  kept  well 
below  the  zone  of  root  development,  permanent  reclamation  cannot 
be  accomplished.  The  temporary  nature  of  the  benefit  that  has 
characterized  many  previous  alkali-reclamation  efforts  has  been  due 
chiefly  to  faults  in  the  drainage  conditions.  Good  drainage  is,  there- 
fore, an  important  phase  of  alkali  reclamation.  In  fact  its  importance 
can  scarcely  be  over-emphasized. 

Soon  after  the  experiments  reported  herein  were  begun  it  became 
evident  that  the  tile-drainage  system,  which  was  then  in  operation 
on  the  experimental  area,  was  not  adequate  for  the  best  results. 
Accordingly,  in  June,  1924,  a  16-inch  well  was  bored  to  a  depth  of 
about  70  feet  at  a  point  near  the  experimental  plots.  Subsequently 
we  have  been  able  to  control  the  ground  water  by  pumping  from  this 
well  throughout  each  irrigation  season.  The  water  is  discharged  into 
a  canal  through  an  underground  pipe  line.  As  was  pointed  out  by 
Weir,(5J  this  scheme  has  been  entirely  successful  from  a  drainage 
standpoint.  Rarely  since  this  well  was  first  put  into  operation  has 
the  level  of  the  ground  water  beneath  the  experimental  plots  been 
nearer  the  surface  than  8  feet. 

A  special  advantage  of  this  method  of  drainage  is  afforded  by 
the  water  itself.  As  will  be  discussed  in  greater  detail  elsewhere,  the 
well  water,  owing  to  its  calcium  content,  is  more  suitable  for  irrigat- 
ing alkali  soil  than  pure  water  or  the  supply  that  is  furnished  by  the 
main  canal  of  this  section.  Moreover,  it  is  available  at  all  seasons  of 
the  year,  whereas  the  canal  supply  is  ^independable  after  midsummer. 
The  irrigation  supply  used  on  these  experiments  is  now  drawn  ex- 
clusively from  this  well. 


BUL.  45o]  RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL 


EXPERIMENTS    WITH    GYPSUM 

Experiments  with  Different  Quantities  of  Gypsum. — In  the  sum- 
mer of  1920  a  series  of  nine  plots,  each  100  by  330  feet  in  size,  was 
staked  out  in  a  badly  affected  part  of  Section  6  of  the  Kearney  Vine- 
yard. Soil  samples  representing  each  foot  down  to  a  depth  of  4  feet 
were  drawn  at  intervals  of  10  feet  throughout  the  greatest  length  of 
the  plots.  Gypsum,  as  recommended  by  Hilgard  many  years  ago,  was 
applied  at  the  rate  of  six  tons  per  acre  to  six  of  the  plots  and  plowed 
under,  after  which  all  of  the  plots  were  flooded  with  water  to  a  depth 
of  about  10  inches  for  a  period  of  three  weeks.  When  sufficiently 
dry  the  soil  was  again  plowed  and  sampled.  Analysis  showed  that 
these  plots  still  contained  considerable  sodium  carbonate.  Therefore, 
three  additional  tons  of  gypsum  per  acre  were  applied  to  three  of 
these  plots  and  all  of  them  were  again  flooded  for  a  period  of  two 
weeks.    Later  the  soil  was  plowed  and  prepared  for  planting. 

Barley  was  sown  in  December  and  harvested  the  following  May. 
Although  the  growth  of  the  barley  showed  that  the  gypsum  treatment 
had  produced  considerable  effect,  the  yields  were  not  satisfactory. 
The  soil  still  contained  considerable  sodium  carbonate.  Hence  in 
June,  1921,  an  additional  application  of  gypsum  was  made  at  the 
rate  of  six  tons  per  acre,  followed  by  heavy  flooding. 

Thus  it  is  seen  that  a  total  of  15  tons  per  acre  of  gypsum  was 
applied  to  three  of  these  plots  and  12  tons  per  acre  to  three  others, 
while  three  plots  were  merely  flooded,  plowed,  and  cultivated  without 
the  application  of  gypsum.  Since  these  applications  of  gypsum  were 
made  in  1920  and  1921  no  further  materials  have  been  applied  to 
these  plots.  They  have  merely  been  cultivated,  irrigated  and  cropped 
as  shown  in  the  tabular  statement  of  the  results  (table  1). 

TABLE  1 

Experiments  with  Gypsum.     Crop  Yields  in  Pounds  per  Acre 


Plot 

Treatment* 

Tons 
per 
acre 

1920, 

Barley 

hay 

1921, 
Barley 

hay 

1922, 

Barley 

hay 

1923, 

Melilotus 

indica  and 

cowpeas 

1924, 

Melilotus 

alba 

1925, 
Alfalfa 

1926 

1927, 
Alfalfa 

3 
4 

5 

Gypsum 

Gypsum 
Untreated 

12 
15 

875 

696 

1,428 

2,154 
2,865 
1,770 

2,438 
3,216 
2,584 

Plowed  under 
as    green 
manure. 

Plowed  under 
as    green 
manure. 

5,422 
5,955 
3,585 

T3 

i    - 

a 

10,728 
11,742 
6,255 

*  The  first  application  of  gypsum  was  made  after  the  barley  was  harvested  in 


8  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

When  this  series  of  experiments  was  begun  the  importance  of  the 
extreme  variability  of  the  Fresno  alkali  soil  was  not  adequately 
appreciated.  It  was  found  later  that  certain  of  these  plots  containued 
spots  of  considerable  size  in  which  there  was  originally  very  little 
alkali  (fig.  1).  Because  of  the  great  variability  of  the  soil,  the  crop 
records  will  be  given  for  only  three  of  the  plots  of  this  series,  i.e., 
plot  3,  treated  with  12  tons  per  acre  of  gypsum ;  plot  4,  treated  with 
]5  tons  per  acre  of  gypsum,  and  plot  5,.  untreated.  These  plots, 
although  not  free  from  variation,  were  more  uniform  as  regards  the 
alkali  distribution  than  the  remaining  plots  of  this  series. 


Fig.  1. — General  view  of  the  area  on  which  the  gypsum  plots  1  to  9  were 
located.  The  photograph  was  taken  in  May,  1920,  just  before  the  experiments 
were  begun.  Note  the  spotted  condition  of  the  soil.  Analysis  showed  that  certain 
spots  on  which  barley  was  growing  were  almost  free  from  alkali,  whereas  the 
barren  areas  contained  much  alkali. 


Barley  was  sown  over  this  entire  area  in  November,  1919.  The 
yields  reported  for  June,  1920,  represent  the  amounts  of  barley  hay 
(grain  and  straw)  that  were  obtained  immediately  preceding  the  time 
when  the  first  application  of  gypsum  was  made.  It  will  be  seen 
that  the  yield  was  light,  the  greatest  amount  being  then  obtained 
from  plot  5,  which  was  used  subsequently  as  a  check  plot.  Barley 
was  again  grown  in  1921  and  1922,  and,  although  increases  were 
obtained,  the  yield  from  each  plot  was  still  unsatisfactory.  The 
appearance  of  the  growing  barlej^  on  the  gypsum  plots  indicated  that 
there  was  an  inadequate  supply  of  available  nitrogen  in  the  soil. 
Accordingly,  Melilotus  indica  and  cowpeas  were  grown  in  1923  (figs. 
2,  3,  and  4)  and  Hubam  clover  (Melilotus  alba)  in  1924.    These  crops 


Bul.  4^5 


RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL 


!) 


were  plowed  under  as  green  manures,  and  alfalfa  was  sown  in  Feb- 
ruary, 1925.  A  fair  stand  was  secured  over  practically  all  of  the 
gypsum  plots  and  also  on  certain  parts  of  the  untreated  plots.     On 


Fig.  2. — CoAvpeas  on  plot  3,  treated  with  12  tons  of  gypsum  per  acre, 
graphed  in  October,  1922. 


Photo- 


Fig.  3. — Cowpeas  on  plot  4,  treated  with  15  tons  of  gypsum  per  acre.  Photo 
graphed  in  October,  1922.  Comparison  of  this  figure  with  figures  2  and  13  shows 
that  15  tons  of  gypsum  gave  better  results  than  either   10  or   12  tons. 


the  other  parts  of  the  untreated  plots  the  alfalfa  seed  failed  to 
germinate.  Owing  to  a  severe  infestation  of  Bermuda  grass  {Cynodon 
dactylon)  these  plots  were  plowed  up  in  December,  1925,  and  kept 
dry  with  frequent  cultivation  throughout  the  following  summer.     By 


10 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


this  means  Bermuda  grass  was  practically  eradicated.  Alfalfa  was 
sown  again  in  October,  1926.  The  yield  in  1927  was  heavy  on  each 
of  the  gypsum  plots,  being  almost  twice  that  of  the  untreated  plot. 


Fig.  4.— Cowpeas  on  check  plot  5.  The  spots  which  show  good  growth  were 
practically  free  from  alkali  at  the  outset.  Although  this  plot  was  subjected  to 
prolonged  leaching  in  1920  and  1921,  the  badly  affected  spots  have  remained 
unproductive.  The  photograph  was  taken  on  the  same  day  as  those  shown  in 
figures  2  and  3. 


Fig.  5. — Alfalfa  on  plot  3,  treated  with  12   tons  of  gypsum  per  acre, 
photograph  was  taken  in  September,  1927. 


The 


The  general  appearance  and  growth  of  the  alfalfa  throughout 
1927  (figs.  5  and  6),  together  with  the  results  obtained  in  laboratory 
studies,  lead  us  to  believe  that  the  choice  of  crops  in  connection  with 


BUL.  455]         RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL 


11 


this  series  of  experiments  was  not  the  best  for  practical  results.  There 
is  good  reason  to  believe  that  had  alfalfa  been  planted  in  1921  after 
the  last  application  of  gypsum  was  made,  or  perhaps  better  still,  had 
Melilotus  alba  been  grown  and  plowed  under  and  this  followed  with 
alfalfa,  satisfactory  yields  of  alfalfa  would  have  been  obtained. 


Fig.  6. — Alfalfa  on  plot  4,  treated  with'  15  tons  of  gypsum  per  acre.     Photo- 
graphed in  September,  1927. 


Fig.    7. — Alfalfa   on   check   plot 
September,  1927. 


Note   the   bare   spots. 


itograplied    in 


There  is  no  reason  to  doubt  the  possibility  of  completely  reclaiming 
this  soil  by  means  of  gypsum  coupled  with  flooding  and  drainage.  It 
is  merely  a  matter  of  using  an  adequate  amount  of  gypsum  and 
leaching  out  the  soluble  salts.     However,  the  more  seriously  affected 


12 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


parts  of  this  soil  will  require  too  large  an  amount  of  gypsum  to  justify 
its  practical  use  at  the  present  prices.  In  localities  where  gypsum 
can  be  obtained  more  cheaply  or  where  the  amount  required  is  not  so 
large,  gypsum  will  be  found  effective  and  profitable  as  a  treatment 
for  black-alkali  soils. 


EXPERIMENTS    WITH    SULFUR 

Comparison  of  Untreated  Sulfur  and  Gypsum. — In  1921  an  experi- 
ment was  begun  with  the  use  of  sulfur.  The  area  chosen  (plot  10, 
100  by  260  feet)  was  almost  entirely  bare  of  vegetation.  Barley  had 
been  sown  the  previous  November,  but  the  seed  failed  to  germinate 


;-S--lk 


Fig.  8. — This  photograph  was  taken  in  April,  1921,  and  shows  the  general  con- 
dition of  plot  10  before  sulfur  was  applied.  The  plant  shown  in  the  foreground 
is  chiefly  an  alkali  weed,  Tissa  salina.  With  the  exception  of  a  few  small  spots 
this  plot  was  entirely  unproductive  before  the  experiment  was  begun. 

over  practically  all  of  this  area  (fig.  8).  The  alkali  conditions  were 
as  extreme  as  could  be  found  anywhere  in  this  field.  Ordinary  finely 
ground  crude  sulfur,  unmixed  with  any  other  material  and  untreated 
in  any  way,  was  applied  at  the  rate  of  3,600  pounds  per  acre.  For 
purpose  of  comparison,  gypsum  was  applied  to  an  adjacent  area  (plot 
11)  (fig.  9)  at  the  rate  of  10  tons  per  acre. 

These  materials  were  applied  and  plowed  under  in  June,  1921, 
after  which  a  light  irrigation  was  given,  this  was  followed  by  shallow 
cultivation,  the  immediate  purpose  being  to  promote  conditions  that 


BUL.  455]         RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL 


13 


are  favorable  for  biological  oxidation.  The  efficiency  of  sulfur  de- 
pends upon  its  being  oxidized  to  sulfate,  and  the  oxidation  is  a  process 
involving  the  action  of  certain  species  of  bacteria.  Since  the  oxidation 
takes  place  gradually,  a  certain  interval  must  elapse  before  sulfur 
can  have  any  effect ;  the  full  effect  where  large  amounts  are  required 
may  be  delayed  for  several  years.     For  this  reason  the  sulfur-treated 


Fig.  9.- — The  condition  of  plot  11  before  gypsum  was  applied.  Although 
severely  affected  with  alkali,  this  plot  was  not  as  uniformly  unproductive  as  was 
plot  10  (fig.  8).  Much  of  the  growth  shown  here  is  an  alkali  weed  (tixsa  salina). 
Photographed  in  April,  1921. 

plot  was  allowed  to  stand  until  late  summer.  Then  both  this  and  the 
adjacent  gypsum  plot  were  flooded  twice,  after  which  they  were 
plowed  and  seeded  to  barley.  The  crops  grown  since  that  time  and 
the  yields  are  reported  in  table  2. 


TABLE  2 
Comparative  Effect  of  Sulfur  and  Gypsum.    Crop  Yields  in  Pounds  per  Acre 


Plot 

Treat- 
ment* 

Amount 
per  acre 

1921, 

Barley 

Hay 

1922, 

Barley 

Hay 

1923, 

Melilotus 

indica  and 

cowpeas 

1924, 
Alfalfa 

1925, 
Alfalfa 

1926, 
Alfalfa 

1927, 
Alfalfa 

10 
11 

Sulfur 
Gypsum 

3,600  pounds 
10  tons 

145 

430 

300 
1,815 

Plowed  under  as 
green  manure. 

4,000t 
l,500t 

18,467 
12,838 

23,658 
14,368 

20,138 
15,103 

*  These  materials  were  applied  after  the  barley  was  harvested  in  1921. 
t  Yield  obtained  from  a  single  cutting  in  September. 


It  will  be  noted  that  the  effects  at  the  end  of  one  year,  as  reflected 
by  the  yield  of  barley  in  1922,  were  not  encouraging.    Gypsum  in  fact 


14 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


was  more  effective  at  that  stage  of  the  experiment  than  sulfur, 
although  neither  produced  a  satisfactory  yield  of  barley  (figs.  10  and 
11).  Cowpeas,  grown  as  a  green  manure  in  1922  soon  after  the 
barley  was  harvested,  gave  the  first  indication  of  benefit  from  the 


■  '*:''''*. 


&§*$£$! 


Fig.  10. — Unsatisfactory  growth  of  barley  on  plot  10  one  year  after  sulfur 
had  been  applied  at  the  rate  of  3600  pounds  per  acre.  Photographed  in  May, 
1922. 


Fig.  11. — Barley  on  plot  11  one  year  after  10  tons  of  gypsum  per  acre  had 
been  applied.  Comparison  of  this  figure  with  figure  10  shows  that  better  effects 
were  produced  by  gypsum  at  this  stage  of  the  experiment  than  by  sulfur.  The 
growth  of  barley  was  spotted.  In  the  foreground  the  maximum  height  of  the 
barley  plants  was  about  18  inches,  and  much  of  the  seed  failed  to  germinate. 


sulfur  treatment.  As  is  shown  in  the  illustrations  (compare  figs.  12 
and  13),  the  growth  of  cowpeas  was  somewhat  greater  on  the  sulfur 
plot  than  on  the  gypsum  plot.     The  beneficial  effect  of  sulfur  and 


Bul.  4f>; 


RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL 


15 


its  superiority  over  gypsum  as  a  treatment  for  this  soil  became  definite 
in  the  growth  of  Mclilotus  indica  in  the  winter  and  spring  of  1923. 
The  Melilotus  seed  germinated  over  practically  all  of  the  sulfur  plot 

■ 


Fig.  12. — Effect  of  sulfur  on  the  growth  of  cowpeas  18  months  after  an 
application  of  3600  pounds  per  acre  was  made.  Photographed  in  October,  1922. 
The  germination  and  growth  of  the  cowpeas  gave  the  first  indication  of  definite 
effect  of  sulfur  on  this  plot. 


Fig.  13. — Effect  of  10  tons  of  gypsum  per  acre  on  the  growth  of  cowpeas. 
Comparison  of  this  photograph  (taken  in  October,  1922)  with  figure  12,  shows 
that  at  this  stage  of  the  experiment  the  effect  of  gypsum  was  less  favorable  than 
that  of  sulfur,  although  the  opposite  was  the  case  with  the  barley  that  was 
grown  previously   (compare  figs.  10  and  11). 


16  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

and  the  growth  was  normal  in  appearance  (fig..  14).  On  the  other 
hand,  the  germination  of  Melilotus  was  poor  on  the  gypsum  plot  and 
the  stand  was.  too  thin  to  justify  its  retention  as  a  green-manure 
crop. 

The  results  that  have  been  obtained  each  year  since  alfalfa  was 
sown  in  February,  1924,  show  clearly  that  sulfur  is  remarkably 
effective  on  this  soil.  The  yields  from  the  sulfur-treated  plot  have 
been  extraordinarily  heavy,  being  fully  twice  the  average  yield  of 
alfalfa  for  the  San  Joaquin  Valley  as  a  whole.    The  tabulated  results 


Fig.  14. — Effect  of  sulfur  on  the  growth  of  Melilotus  indica  two  years  after 
an  application  of  3600  pounds  per  acre  was  made.  Note  that  with  the  exception 
of  one  small  spot  the  growth  was  vigorous  throughout  this  plot.  Photographed 
May,  1923. 

shown  in  table  2,  together  with  the  series  of  photographs  of  this  plot 
(figs.  8,  10,  12,  14,  and  15)  are  self-explanatory.  The  latter  presents 
a  striking  illustration  of  the  effects  of  sulfur. 

It  will  be  noted  that  the  sulfur  plot  has  yielded  approximately 
50  per  cent  more  alfalfa  hay  than  the  gypsum  plot  of  this  experiment 
(compare  figures  15  and  16).  However,  it  is  probable  that  a  heavier 
application  of  gypsum  (more  than  10  tons  per  acre)  would  have  given 
better  results.  This  point  will  be  more  fully  discussed  in  a  later 
section  of  this  bulletin. 

In  this  connection  it  seems  desirable  to  point  out  that  the  reduced 
yield  of  alfalfa  obtained  in  1927,  as  compared  with  that  of  1926, 
was  probably  not  due  to  a  return  of  alkali  into  the  soil,  but  was 
caused  chiefly  by  the  spread  of  Bermuda  grass  over  this  plot.  In 
this  and  other  sections  of  California  the  rapid  spread  of  Bermuda 
grass  makes  it  difficult  to  maintain  a  good  stand  of  alfalfa  longer  than 


Bul.  455]  RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL 


17 


three  or  four  years.  However,  the  growth  of  this  grass  is  not  confined 
to  alkali  soil,  although  the  effect  may  be  more  serious  on  alkali  soil 
for  the  reason  that  alfalfa  is  more  sensitive  than  Bermuda  grass  to 
alkali. 


Fig.  15. — Effect  of  3600  pounds  of  sulfur  per  acre  on  the  growth  of  alfalfa. 
The  corresponding  effect  of  gypsum  at  this  stage  of  the  experiment  is  shown 
in  figure  16.     Photographed  in  May,  1925. 


Fig.  16. — The  effect  of  10  tons  of  gypsum  per  acre  on  the  growth  of  alfalfa. 

Note  the  spotted  appearance.  On  the  lighter-colored  areas  the  alfalfa  seed 
failed  to  germinate.  Later  Bermuda  grass  spread  over  these  spots.  Comparison 
with  figure  15  shows  that  sulfur  was  much  more  effective  than  gypsum.  Photo- 
graph taken  in  May,  1925. 


Experiments  with  Inoculated  Sulfur. — A  second  sulfur  experi- 
ment (plots  21  to  25)  was  begun  in  May,  1923,  in  cooperation  with 
Charles  D.  Samuels. (3)     As  in  the  sulfur  experiment  discussed  above, 


18 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


the  area  chosen  for  this  experiment  was  also  badly  affected  with  alkali. 
A  series  of  five  plots,  each  40  by  135  feet  in  size,  was  staked  out, 
sampled,  and  prepared  for  irrigation.  Sulfur  was  applied  to  four 
of  these  plots,  the  fifth  being  left  untreated  as  a  check.  The  sulfur 
used  in  this  series  was  finely  ground  and  had  been  artificially 
inoculated  with  a  culture  of  sulfur-oxidizing  bacteria.  This  material 
was  applied  at  the  rate  of  approximately  two  tons  per  acre.  In  addi- 
tion to  sulfur,  gypsum  was  also  applied  to  plot  21  at  the  rate  of 
2.5  tons  per  acre,  and  ground  limestone  to  plot  22  at  the  rate  of  two 
tons  per  acre. 

These  materials  were  plowed  under,  after  which  the  plots  were 
allowed  to  lie  fallow  until  February,  1925,  with  only  an  occasional 
light  irrigation  and  shallow  cultivation.  They  were  then  flooded 
twice,  plowed,  and  sown  to  Melilotus  alba.  Fairly  good  growth  was 
obtained  on  each  of  the  sulfur-treated  plots  but  the  seed  failed  to 
germinate  on  the  check  plot.  The  Melilotus  alba  was  plowed  under 
as  a  green  manure  in  September,  1925,  and  alfalfa  was  sown  in 
February,  1926.  A  good  stand  was  secured  on  each  of  the  sulfur- 
treated  plots,  but  the  alfalfa  seed  failed  to  germinate  on  the  check 
plot  (compare  figs.  17  and  18).  As  shown  in  table  3,  heavy  yields 
of  alfalfa  have  since  been  harvested  from  these  plots. 

TABLE  3 
Effect  of  Inoculated  Sulfur.     Crop  Yields  in  Pounds  per  Acre 


Plot 

Materials* 

Tons 
per  acre 

1925, 
Hubam  clover 

1926, 
Alfalfa 

1927, 
Alfalfa 

21 

22 
23 

f        Sulfur 

)        Gypsum 

f        Sulfur 

\        Lime 

Untreated 

Sulfur 

Sulfur 

2             \ 

VA       \ 

2             \ 
2             J 

Plowed 
under 

as 
green 

manure 

10,916 

11,500 

83 
12,166 
9,583 

17,549 

18,897 

615 

24 
25 

2 
2 

18,848 
17,031 

*  Applied  in  May,  1923. 


It  will  be  seen  that  practically  the  same  yields  of  alfalfa  have  been 
obtained  from  each  of  the  sulfur-treated  plots  of  this  series.  Since, 
in  addition  to  sulfur,  gypsum  was  applied  to  plot  21  and  ground 
limestone  to  plot  22,  whereas  sulfur  alone  was  applied  to  plots  24 
and  25,  it  is  clear  that  the  effects  produced  in  each  case  have  been 
due  chiefly  to  sulfur.  The  chemical  studies  necessary  to  determine 
whether  there  is  a  detectable  chemical  difference  in  the  soil  due  to 
the  gypsum  have  not  yet  been  made. 


BUL.  455]         RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL  19 


Fig.  17. — Ineffectiveness  of  leaching  when  unaccompanied  by  other  treatment. 
The  plots  to  the  right  and  left  of  plot  23  were  treated  with  sulfur  in  May,  1923. 
Photograph  taken  in  October,  1926. 


Fig.  18. — Effect  of  inoculated  sulfur  on  alfalfa.  The  material  was  applied 
in  May,  1923,  and  the  photograph  was  taken  in  October,  1926.  Comparison  of 
this  figure  with  figures  15  and  19  shows  that  the  effect  of  uninoculated  sulfur 
was  similar  to  that  of  inoculated  sulfur.  The  same  is  shown  in  the  tabular  state- 
ment of  yields. 


20  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Sulfur  Experiment  on  a  Larger  Area. — A  third  experiment  with 
sulfur  was  begun  in  December,  1924,  on  an  area  of  about  seven  acres 
(plots  26-44).  Finely  ground  uninoculated  sulfur  was  applied  at  the 
rate  of  one  ton  per  acre  and  disked  in.  Melilotus  alba  was  sown  in 
March,  1925,  and  a  fair  stand  and  good  growth  were  secured  except 
on  the  most  seriously  affected  spots.  This  crop  was  plowed  under 
as  a  green  manure  in  September,  1925,  and  barley  was  planted  the 
following  December.  The  barley  crop  was  not  weighed,  but  the 
growth  was  vigorous  on  all  parts  of  the  treated  area  with  the  excep- 
tion of  a  few  small  spots.  After  the  barley  crop  had  been  harvested, 
the  soil  was  plowed  and  allowed  to  remain  dry  during  the  summer 


Fig.  19. — Alfalfa  on  the  seven-acre  area  treated  with  sulfur  in  December, 
1924,  at  the  rate  of  1  ton  per  acre.  Alfalfa  was  sown  in  October,  1926,  and 
photographed  in  September,  1927.  This  plot  has  not  been  leached  at  any  time 
since  the  experiment  was  begun.  The  irrigation  water  was  applied  at  two-week 
intervals  throughout  the  hotter  months  of  1927. 

of  1926,  and  in  October  alfalfa  was  sown.  The  seed  germinated 
well,  and  vigorous  growth  has  resulted.  The  first  cuttings  made  in 
1927  were  not  weighed.  The  average  yield  per  cutting  after  June  1, 
1927,  was  2,445  pounds  per  acre,  which  is  usually  considered  to  be 
a  satisfactory  yield. 

In  this  experiment  the  soil  has  not  been  as  heavily  leached  as  was 
the  case  with  the  previous  experiments.  Since  alfalfa  is  usually 
irrigated  by  the  flooding  system,  the  attempt  is  being  made-  to  leach 
out  the  soluble  salts  and  wash  down  the  sulfur-oxidation  products 
by  means  of  ordinary  irrigation.  The  results  to  date  (February, 
1928)  indicate  that  the  experiment  will  be  successful  (fig.  19). 


BUL.  455]  RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL 


21 


Sulfur  with  Stable  Manure  and  with  Ground  Limestone. — A 
fourth  sulfur  experiment  was  begun  on  plots  16  and  19  in  October, 
1925,  using  ordinary  finely  ground  untreated  sulfur,  similar  to  that 
which  was  applied  to  plot  10  in  1921.  The  application  was  made  at 
the  rate  of  1000  pounds  per  acre.  In  1922  plot  19  had  been  treated 
with  stable  manure  and  plot  16  with  ground  limestone,  the  applica- 
tion of  each  being  followed  by  heavy  leaching.  The  effects  of  the 
manure  and  ground  limestone  had  not  been  discernible  either  in  the 
growth  of  barley  in  1923  and  1924  or  in  that  of  cowpeas  sown  in  the 
summer  of  1923  or  in  that  of  Melilotus  alba  sown  in  May,  1925.  The 
sulfur  was  applied  and  plowed  under  in  October,  1925,  and  alfalfa 
was  sown  in  February,  1926.  The  germination  was  good  on  plot  19 
and  fair  on  plot  16. 

TABLE  4 

The  Effect  of  Sulfur  on  Soil  Previously  Treated  with  Ground  Limestone 

and  Stable  Manure.    Yields  in  Pounds  per  Acre 


Plot 

Material 
applied* 

Amount 
per  acre 

1923, 
Barley 

1924, 
Barley 

1925, 
Hubam  clover 

1926, 
Alfalfa 

1927, 
Alfalfa 

..I 

■ 

20 

Sulfur 

Ground  limestone 

Sulfur 

Manure 

1,000  lbs. 

9  tons 

1,000  lbs. 

18  tons 

)     108 

I     o 

J 

0 

30 
24 
15 

Plowed  under 
as  green 
manure 

1,800 

10,440 

312 

11,634 

20,022 

2,502 

*  The  ground  limestone  and  manure  were  applied  in  June,  1922;  the  sulfur  was  applied  in  November, 
1925. 

In  certain  respects  this  sulfur  experiment,  particularly  the  plot 
that  was  treated  with  stable  manure  three  and  one-half  years  pre- 
viously, has  given  the  most  striking  results  of  all  in  this  field  (fig.  20). 
The  rate  of  sulfur  oxidation,  as  indicated  by  the  evidence  of  sulfate 
formation  in  the  soil,  has  been  especially  pronounced.  As  is  shown 
in  table  4,  heavy  yields  of  alfalfa  were  obtained  from  this  plot  in 
1926  and  1927.  The  untreated  check  plot  of  this  series  has  been  a 
practical  failure  so  far  as  the  growth  of  alfalfa  is  concerned  (fig.  21). 

At  no  time  since  the  sulfur  was  applied  in  October,  1925,  have 
these  plots  been  heavily  flooded.  They  were  irrigated  twice  each 
month  during  the  spring  and  summer  of  1926  and  approximately  once 
every  three  weeks  subsequently.  As  is  shown  by  the  chemical  analyses, 
the  effect  of  the  sulfur  has  not  yet  penetrated  as  deeply  on  plot  19 
as  it  has  on  plot  10.  This  is  probably  due  both  to  the  absence  of 
heavy  flooding  and  to  the  briefer  period  that  has  elapsed  since  the 
sulfur  was  applied. 


22 


UNIVERSITY  OF   CALIFORNIA — EXPERIMENT   STATION 


Fig.  20. — Alfalfa  as  affected  by  the  combined  use  of  stable  manure  applied 
at  the  rate  of  18  tons  per  acre  in  May,  1922,  and  of  sulfur  applied  at  the  rate 
of  1000  pounds  per  acre  in  October,  1925.  The  alfalfa  was  sown  in  February, 
1926,  and  was  photographed  in  October,  1926. 


J^J*4#$SRSf:- 


Fig.  21. — Failure  of  leaching  as  a  practical  method  of  reclamation.     Alfalfa 
was  sown  in  February,  1926,  and  photographed  in  September,  1927. 


BUL.  455]  RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL 


23 


EXPERIMENTS    WITH    IRON    SULFATE    AND    ALUM 

Previous  laboratory  experiments(2)  gave  results  which  indicated 
that  iron  sulfate  and  alum  might  prove  effective  on  this  soil. 
Accordingly  plot  17  was  treated  in  August,  1922,  with  iron  sulfate 
at  the  rate  of  approximately  nine  tons  per  acre,  and  plot  18  with 
alum  at  the  rate  of  11  tons  per  acre.  Plot  14  was  untreated.  Immedi- 
ately after  these  materials  were  applied,  the  soil  was  heavily  flooded. 
Barley  was  planted  the  following  December.  The  seed  germinated 
well  and  the  barley  seedlings  grew  vigorously  for  a  few  weeks  on 


.  :  .    ,"  '  *    "'  '•  ; 


Fig.  22. — Failure  of  leaching  as  a  practical  method  of  reclamation.     Alfalfa 
was  sown  in  February,  1926,  and  photographed  in  September,  1927. 

each  of  the  treated  plots.  Later  the  plants  became  pale  in  color  and 
the  yield  was  light.  Cowpeas  planted  after  the  barley  was  harvested 
in  May,  1923,  also  germinated  well  on  both  of  the  treated  plots,  but 
later  the  plants  became  pale  and  unthrifty  on  the  alum  plot.  Barley 
was  again  grown  in  1924  but  the  yield  was  inferior.  The  plants 
presented  an  appearance  indicative  of  a  deficiency  of  available  nitro- 
gen in  the  soil.  Alfalfa  was  sown  in  February,  1926.  The  seed 
germinated  well  and  the  subsequent  growth  has  been  normal  in 
appearance.  As  shown  in  table  5  the  untreated  check  plot  has 
remained  almost  entirely  unproductive,  whereas  the  iron  sulfate  and 
alum  plots  have  given  good  yields  of  alfalfa  (compare  figs.  22,  23, 
and  24). 


24 


UNIVERSITY    OF   CALIFORNIA EXPERIMENT    STATION 


TABLE  5 
Effect  of  Iron  Sulfate  and  Alum.     Yields  in  Pounds  per  Acre 


Plot 

Material 
applied 

Tons 
per  acre 

1923, 
Barley 

1924, 
Barley 

1925, 
Hubam  clover 

1926, 
Alfalfa 

1927, 
Alfalfa 

14 

528 
2,406 
1,014 

192 

1,101 

801 

]    Plowed  under    | 
f        as  green        < 
J          manure          ( 

60 
11,880 
10,320 
12,739 

618 

17 
18 

Iron  sulfate* 

9 
11 
5 

19,176 

18,762 

45 

Iron  sulfatet 

20,504 

*  Applied  in  June,  1922. 


t  Applied  in  October,  1925. 


Fig.   23. — Effect  on  alfalfa  of  iron   sulfate  applied  in  August,   1922,  at  the 
rate  of  9  tons  per  acre.     Photographed  in  September,  1927. 


«^~ . 


Fig.  24. —  Effect  on  alfalfa  of  alum  applied  in  August,   1922,  at  the  rate  of 
11  tons  per  acre.     Photographed  in  September,  1927. 


BUL.  455]  RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL  25 

Chemical  studies  made  on  samples  of  soil  from  these  plots  prove, 
as  will  be  reported  elsewhere/1 }  that  both  the  iron  sulfate  and  alum 
have  brought  about  important  chemical  changes  in  the  soil.  In  each 
case  the  chemical  changes  have  been  similar  to  those  in  the  sulfur- 
treated  plots  referred  to  above. 

A  second  experiment  with  iron  sulfate  (plot  45)  was  begun  in 
October,  1925,  the  material  being  applied  at  the  rate  of  five  tons  per 
acre.  After  one  flooding  this  plot  was  seeded  to  alfalfa  in  the  follow- 
ing February.  The  subsequent  yields  of  alfalfa  have  been  heavy,  the 
extraordinary  yield  of  over  six  tons  per  acre  having  been  obtained  in 
1926,  the  first  year  after  the  alfalfa  was  sown  (see  fig.  25).  In  1927 
good  yields  were  again  obtained. 


Fig.  25. — Effect  on  alfalfa  of  iron  sulfate  applied  in  October,   1925,  at   the 
rate  of  5  tons  per  acre.     Photographed  in  September,  1927. 


EFFECT    OF    LEACHING    WITHOUT    OTHER    TREATMENT 

As  stated  already,  attempts  made  in  1911  and  1915  to  reclaim  this 
soil  by  flooding  and  drainage  were  unsuccessful.  In  order  to  test 
the  leaching  method  further,  three  plots  in  the  gypsum  series  were 
left  untreated.  They  were  flooded  and  otherwise  subjected  to  the 
same  cultural  treatment  as  the  gypsum  plots.  The  heavy  floodings 
to  which  these  plots  were  subjected  in  1920  and  1921  afforded  a 
practical  test  of  the  leaching  method  of  reclamation.  One  plot  in 
connection  with  the  experiment  with  iron  sulfate  and  alum  and  one 
in  each  of  the  sulfur  series  of  1923  and  1925  were  also  left  untreated. 


26  UNIVERSITY   OF   CALIFORNIA — EXPERIMENT   STATION 

No  material  has  been  applied  to  these  plots,  but  otherwise  they  too 
have  been  plowed,  flooded,  cultivated,  and  irrigated  just  as  the  other 
plots  of  these  series. 

Parts  at  least  of  one  of  the  check  plots  in  the  gypsum  series  have 
been  markedly  improved,  as  is  shown  by  the  crop  records  and  the 
chemical  analyses.  On  the  other  hand,  several  spots  of  considerable 
size  on  the  other  check  plots  of  this  series  have  been  benefited  very 
little,  if  at  all.  Neither  the  check  plot  of  the  iron  sulfate  and  alum 
series  (plot  14),  nor  those  of  the  sulfur  series  (plots  20  and  23)  have 
shown  more  than  the  most  meager  indication  of  improvement. 

Although  these  experiments  show  that  it  is  possible  to  improve 
the  crop-producing  power  of  a  part  at  least  of  this  soil  by  leaching 
without  adding  other  materials,  and,  as  will  be  shown  in  another 
paper,  it  is  even  possible  by  this  means  to  effect  its  complete  con- 
version into  normal  soil,  the  difficulty  of  so  doing  is  considerable. 
The  superior  effects  that  may  readily  be  obtained  by  the  use  of  sulfur 
and  other  materials,  together  with  the  fact  that  certain  fundamentally 
important  losses  are  sustained  by  the  soil  when  it  is  subjected  to 
prolonged  leaching,  strongly  argue  against  placing  sole  reliance  on 
the  leaching  method  of  reclamation.  Where  sulfur  and  possibly  other 
materials  are  applied  it  is  probably  best  to  limit  the  leaching  to  the 
amount  that  is  required  to  remove  the  soluble  salts. 

As  stated  already,  the  failure  of  leaching  as  a  practical  method 
of  reclamation  is  due  to  the  fact  that,  unless  some  special  material 
is  applied  in  addition  to  water,  the  necessary  changes  in  the  clay 
constituents  of  this  soil  take  place  very  slowly.  Where  the  irrigation 
supply  contains  calcium  salts,  the  required  amount  of  gypsum,  sulfur, 
or  other  materials  will  be  correspondingly  reduced,  and  if  the  water 
contains  considerable  calcium  salts,  mere  leaching  may  suffice  to  bring 
about  complete  reclamation.  This  appears  to  be  the  case  with  a 
certain  black-alkali  soil  near  Salt  Lake  City,  Utah. 


CHEMICAL  CHANGES    IN   THE   SOIL 

The  soil  samples  that  were  drawn  from  these  plots  before  the 
various  materials  were  applied  and  the  corresponding  samples 
drawn  subsequently,  have  been  analyzed  for  water-soluble  salts. 
Although  the  chemical  changes  that  are  requisite  to  the  complete 
reclamation  of  this  soil  must  involve  the  clay  constituents  as  well  as 
the  soluble  salts,  a  determination  of  the  latter  has  distinct  value. 
Such  determination  not  only  affords  proof  concerning  the  changes 


BUL.  455]  RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL 


27 


in  the  soluble  salts  and  the  effectiveness  of  the  leaching  per  se,  but 
also  gives  valuable  indication  as  to  the  progress  of  the  changes  in  the 
clay  constituents. 

A  separate  paper (1)  will  be  devoted  to  a  more  theoretical  discussion 
of  the  chemical  changes  that  have  taken  place  in  these  plots.  At 
present  it  may  be  pointed  out  that  a  decrease  in  the  sodium  carbonate 
content  takes  place  concurrently  with  the  needed  changes  in  the  clay. 
The  changes  found  in  soluble  carbonate  and  calcium  tell  us  at  once 
whether  a  given  treatment  is  proving  effective.  The  chlorin  deter- 
minations give  the  necessary  evidence  as  to  the  effectiveness  of  the 
leaching.  The  averages  of  the  analyses  of  the  samples  from  certain 
plots  are  reported  in  tables  6,  7,  and  8.  It  will  be  noted  that  each 
of  these  treatments  has  brought  about  a  reduction  in  the  content  of 
chlorin  and  soluble  carbonate.  There  is,  however,  a  marked  difference 
in  the  extent  to  which  the  changes  have  taken  place  in  the  different 
plots. 

TABLE  6 
Chemical  Effect  of  Gypsum 


Depth 

of 
samples 

in 
inches 

Parts  per  million 

C03 

CI 

Ca 

May 

1920* 

Oct. 
1921 

Dec. 

1927 

May 
1920* 

Oct. 
1921 

Dec. 

1927 

May 

1920* 

Oct. 
1921 

Dec. 

1927 

Plot  3,         f 
gypsum,      j 

12  tons 
per  acre        [ 

0-12 
12-24 
24-36 
36-48 

253 
116 
143 
110 

5 

33 
96 
84 

0 
0 

45 
135 

248 
256 
227 
250 

30 
42 
17 
24 

18 
27 

27 
35 

Trace 
Trace 
Trace 
Trace 

101 

22 

Trace 

Trace 

45 

25 

Trace 

Trace 

Plot  4,         f 
gypsum,       1 

15  tons 
per  acre        ( 

0-12 
12-24 

24-36 
36-48 

283 
147 
128 
44 

17 
73 
105 
60 

0 

0 

75 

105 

116 
162 
137 
114 

16 
18 
22 
32 

18 
18 
27 
35 

Trace 
Trace 
Trace 
Trace 

76 

13 

Trace 

Trace 

27 
Trace 
Trace 
Trace 

Plot  5,         1 
untreated 

0-12 
12-24 
24-36 
36-48 

315 
146 
127 
44 

99 
89 
146 
86 

45 

90 

240 

210 

220 
220 
205 
120 

13 
35 
145 
194 

27 

53 

177 

204 

Trace 
Trace 
Trace 
Trace 

Trace 
Trace 
Trace 
Trace 

Trace 
Trace 
Trace 
Trace 

*  The  analyses  for  1920  represent  the  original  soil  before  the  experiment  was  begun. 

Although  the  determination  of  the  average  composition  of  the 
different  plots  before  and  after  the  materials  were  applied  brings 
out  the  relative  effect  of  the  different  treatments,  this  method  fails  to 
present  a  true  picture  of  the  chemical  variation  within  a  given  plot. 
For  example,  there  are  several  spots  of  considerable  size  on  plot  11, 
which  was  treated  with  gypsum  at  the  rate  of  10  tons  per  acre,  that 
still  contain  considerable  sodium  carbonate  and  only  traces  of  soluble 


28 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


calcium.  This  fact  is  not  indicated  by  the  analyses  of  this  plot 
reported  in  table  7.  On  these  spots  alfalfa  has  not  made  satisfactory 
growth.  On  the  other  hand,  the  improved  chemical  conditions  and 
the  growth  of  alfalfa  have  been  much  more  uniform  where  either 
12  or  15  tons  of  gypsum  per  acre  were  applied.  A  similar  uniformity 
of  effect  has  resulted  from  the  application  of  sulfur,  iron  sulfate,  and 
alum. 

TABLE  7 
Comparative  Chemical  Effect  of  Sulfur  and  Gypsum 


Depth 

of 
samples 

in 
inches 

Parts  per  million 

Treatment 

C03 

CI 

Ca 

Apr. 
1921* 

Oct. 
1921 

Dec. 

1925 

Dec. 

1926 

Apr. 
1921* 

Oct. 
1921 

Dec. 
1925 

Dec. 
1926 

Apr. 
1921* 

Oct. 
1921 

Dec. 
1925 

Dec. 

1926 

Plot  10,     f 

0-12 

346 

144 

3 

0 

544 

48 

50 

36 

Trace 

Trace 

32 

28 

sulfur,       1 

12-24 

179 

141 

35 

16 

440 

76 

50 

30 

Trace 

Trace 

13 

18 

3,600  lbs. 

24-36 

158 

181 

109 

109 

248 

235 

75 

40 

Trace 

Trace 

Trace 

Trace 

per  acre      ( 

36-48 

127 

134 

154 

204 

174 

368 

106 

55 

Trace 

Trace 

Trace 

Trace 

Plot  11,       f 

0-12 

221 

37 

32 

16 

491 

35 

50 

32 

Trace 

27 

15 

21 

gypsum,     j 

12-24 

162 

92 

124 

106 

376 

41 

67 

36 

Trace 

Trace 

Trace 

Trace 

10  tons      1 

24-36 

127 

88 

221 

235 

264 

105 

128 

53 

Trace 

Trace 

Trace 

Trace 

per  acre      [ 

36-48 

64 

79 

178 

273 

201 

209 

244 

93 

Trace 

Trace 

Trace 

Trace 

The  analyses  for  April,  1921,  represent  the  original  soil  before  the  experiment  was  begun. 

TABLE  8 
Chemical  Effect  of  Iron  Sulfate  and  Alum 


Depth 

of 
samples 

in 
inches 

Par 

s  per  mi 

lion 

COs 

CI 

Ca 

May 

1922* 

Nov. 
1922 

Dec. 

1926f 

May 
1922* 

Nov. 
1922 

Dec. 

1926t 

May 
1922* 

Nov. 
1922 

Dec. 

1926f 

f 

0-12 

356 

185 

210 

598 

40 

70 

Trace 

Trace 

Trace 

Plot  14,        1 

12-24 

132 

72 

225 

246 

260 

177 

Trace 

Trace 

Trace 

untreated 

24-36 

50 

56 

90 

285 

161 

301 

Trace 

Trace 

Trace 

I 

36-48 

37 

56 

60 

348 

77 

230 

Trace 

Trace 

Trace 

Plot  17,        ( 

0-12 

313 

20 

47 

349 

69 

32 

Trace 

32 

Trace 

iron  sulfate,    1 

12-24 

95 

21 

78 

204 

78 

47 

Trace 

Trace 

Trace 

9  tons 

24-36 

49 

51 

71 

134 

117 

134 

Trace 

Trace 

Trace 

per  acre       [ 

36-48 

27 

16 

27 

86 

138 

128 

Trace 

Trace 

.19 

Plot  18,        f 

0-12 

298 

2 

41 

314 

109 

65 

Trace 

256 

Trace 

alum,          ) 

12-24 

113 

39 

58 

160 

104 

93 

Trace 

Trace 

12 

11  tons 

24-36 

48 

17 

57 

138 

173 

159 

Trace 

Trace 

32 

per  acre       { 

36-48 

24 

28 

26 

121 

98 

132 

Trace 

Trace 

50 

*  The  analyses  for  May,  1922,  represent  the  original  soil  before  the  experiment  was  begun, 
t  These  samples  of  plot  14  were  drawn  in  December,  1927. 


BUL.455]  RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI   SOIL  29 

Satisfactory  growth  of  crops  in  this  soil  is  conditioned  upon  the 
reduction  of  soluble  carbonate  (C03),  at  least  in  the  upper  layers 
of  the  soil,  to  less  than  50  parts  per  million  and  the  presence  of  an 
appreciable  amount  of  soluble  calcium.  The  analyses  show  that  the 
chemical  changes  brought  about  by  gypsum,  sulfur,  iron  sulfate,  and 
alum  were  in  these  directions. 

Several  years  ago  theoretical  consideration  of  this  problem  con- 
vinced us  that  each  of  these  materials,  if  applied  in  sufficient  amounts, 
would  inevitably  produce  similar  changes  in  the  soluble  carbonate  and 
the  clay  constituents  of  the  soil.  A  special  study  of  these  plots  has 
fully  verified  this  deduction/1'  In  the  case  where  gypsum  was 
applied,  the  soluble  carbonate  has  been  converted  into  insoluble 
calcium  carbonate,  and  obviously  the  soluble  calcium  was  furnished 
by  the  gypsum.  On  the  other  hand,  an  important  part  of  the  bene- 
ficial action  of  sulfur,  iron  sulfate,  and  alum  depends  on  the  presence 
of  calcium  carbonate  in  the  soil.  It  is  true  each  of  these  materials 
may  neutralize  the  soluble  carbonate,  but  the  fundamentally  important 
transformation  of  the  clay  constituents  necessitates  either  that 
insoluble  calcium  minerals  of  the  soil  be  made  soluble  or  else  that 
soluble  calcium  be  added  to  the  soil. 

As  pointed  out  already,  the  oxidation  products  of  sulfur  will 
neutralize  the  soluble  carbonate  and  dissolve  calcium  carbonate,  and 
the  calcium  thus  made  soluble  will  in  turn  bring  about  the  needed 
changes  in  the  clay  constituents.  In  the  case  of  iron  sulfate  and 
alum  the  reactions  are  essentially  the  same.  These  materials  are  acidic 
owing  to  hydrolysis,  the  important  hydrolytic  product  being  sulfuric 
acid  in  both  cases.  It  is  this  latter  compound  that  brings  about  the 
important  chemical  transformations  in  the  soil. 

Thus  it  will  be  seen  that  the  success  of  treatments  with  sulfur,  iron 
sulfate,  and  alum  depend  on  the  presence  of  calcium  carbonate  or 
some  other  readily  decomposable  calcium  mineral  in  the  soil.  Other- 
wise the  essential  changes  in  the  clay  cannot  be  produced  by  these 
materials.  Fortunately,  the  Fresno  soil  contains  calcium  carbonate 
in  amounts  sufficient  for  the  purpose.  In  fact,  American  alkali  soil 
usually  contains  more  or  less  calcium  carbonate. 

As  Samuels  pointed  out,(3)  sulfur,  alum,  and  iron  sulfate  should 
ultimately  produce  better  effects  than  a  chemically  equivalent  amount 
of  gypsum,  because  these  materials  are  able  to  bring  more  calcium 
into  solution  from  the  carbonate  form  than  is  contained  in  the 
gypsum. 


30  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


EFFECTS   ON   THE    PHYSICAL   CONDITION   OF   THE   SOIL 

It  is  well  known  that  the  physical  condition  of  black-alkali  soil  is 
almost  always  poor.  The  clay  particles  are  cleflocculated,  or  readily 
become  so,  and  water  penetrates  very  slowly.  After  the  major  part 
of  the  soluble  salts  has  been  leached  out,  much  of  the  irrigation  water 
may  stand  on  the  surface  until  it  evaporates.  When  dry  the  soil 
becomes  extremely  hard.  Under  the  plow  it  breaks  into  large  clods 
and  a  good  seed  bed  is  difficult  to  prepare. 

When  the  experiments  were  begun  this  was  the  general  condition 
of  all  of  these  plots ;  it  is  still  the  condition  of  check  plots  14,  20,  and 
23  and  parts  of  check  plots  2,  5,  and  8.  On  the  other  hand,  all  of  the 
treated  plots,  except  a  few  small  spots  in  plot  11  (treated  with 
gypsum)  and  a  small  part  of  plot  16  (treated  with  CaC03  and  sulfur), 
have  become  friable,  and  water  now  penetrates  them  freely. 

The  improved  physical  condition  was  noted  soon  after  the  gypsum 
was  applied  and  was  most  pronounced  where  the  largest  amount  was 
applied.  Still  more  striking  physical  effects  were  produced  by  iron 
sulfate  and  alum.  Where  these  materials  were  added  the  water  that 
has  been  applied  has  been  absorbed  rapidly.  On  the  other  hand,  the 
beneficial  effect  of  sulfur  was  not  immediate,  in  some  cases  the  lapse 
of  a  year  or  more  being  required.  Later,  however,  the  physical 
condition  of  the  soil  was  markedly  improved  by  sulfur. 

With  each  of  these  materials  the  physical  effect  is  dependent  upon 
the  chemical  reactions  that  have  already  been  discussed,  and  until 
these  reactions  proceed  beyond  a  certain  point  the  physical  condition 
of  the  soil  may  not  show  any  improvement  whatever.  When  the 
chemical  conditions  are  made  favorable  for  plant  growth  the  physical 
factors  in  this  type  of  soil  will  probably  take  care  of  themselves. 

GENERAL    DISCUSSION 

From  the  preceding  discussion  it  is  apparent  that  each  of  several 
different  materials  may  be  effective  as  a  treatment  for  the  Fresno 
type  of  black-alkali  soil.  The  cost,  however,  is  not  the  same.  Sulfur 
is  by  far  the  most  economical  material  that  we  have  used  in  these 
experiments.  An  average  application  of  not  more  than  one  ton  per 
acre  will  probably  suffice.  At  this  rate  the  cost  of  the  sulfur  should 
not  exceed  $45.00  an  acre.  It  is  possible  that  a  less  expensive  form 
of  sulfur  than  that  used  in  these  experiments  may  give  equally  good 
results.     By  combining  the  use  of  sulfur  with  barnyard  manure  or 


BUL.  455]  RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL  31 

with  the  growing  of  an  alkali-resistant  legume,  such  as  Melilotus  alba, 
it  is  possible  that  an  application  of  1000  pounds  of  sulfur  per  acre 
will  give  good  results. 

It  seems  probable  that  black-alkali  soils  of  other  types  can  also  be 
successfully  treated  with  sulfur,  but  it  is  certain  that  the  amount 
of  sulfur  required  for  the  best  results  will  vary  in  different  localities 
depending  on  the  content  of  sodium  carbonate  and  the  amount  of 
replaceable  sodium  present  in  the  clay  materials  of  the  soil.  More- 
over, there  is  no  direct  proportionality  between  the  content  of  sodium 
carbonate  and  that  of  replaceable  sodium.  Generally  speaking,  heavy 
types  of  black-alkali  soil  will  require  more  sulfur  than  light  types 
which  contain  similar  amounts  of  soluble  carbonate,  because  the 
former  are  likely  to  contain  the  greater  amounts  of  replaceable 
sodium,  but  this  is  not  necessarily  the  case.  In  any  event,  it  is  im- 
portant for  those  engaged  in  black-alkali  soil  reclamation  to  realize 
that  the  required  amount  of  sulfur  is  not  necessarily  determined 
solely  by  the  content  of  sodium  carbonate. 

In  connection  with  the  use  of  sulfur  it  is  important  to  bear  in 
mind  that  a  period  of  several  months,  perhaps  a  year  or  more,  will 
be  required  before  the  full  effects  will  become  manifest.  Sulfur  must 
undergo  oxidation  before  it  can  produce  any  beneficial  effect,  and  the 
oxidation  is  a  relatively  slow  process. 

The  results  thus  far  obtained  lend  no  support  to  the  view  that 
artificial  inoculation  of  sulfur  with  oxidizing  bacteria  is  either  neces- 
sary or  beneficial  on  this  soil.  It  is  evident  that  one  or  more  of  the 
species  of  sulfur-oxidizing  bacteria  occur  in  an  active  form  in  this 
soil,  and  nothing  appears  to  be  gained  by  special  inoculation.  This 
question  is  now  being  further  investigated  and  the  results  will  be 
reported  later. 

It  seems  desirable  to  point  out  that  sulfur  is  not  recommended 
for  any  and  all  types  of  alkali  soil.  At  present  it  can  be  safely  recom- 
mended only  for  black-alkali  types  and  alkali  soils  which  contain 
relatively  large  amounts  of  replaceable  sodium.  The  amount  to  be 
applied  will  depend  on  the  content  of  sodium  carbonate  and  replace- 
able sodium.  We  do  not  recommend  sulfur  where  the  soil  contains  a 
considerable  amount  of  soluble  calcium  salt.  Moreover,  it  is  doubtful 
whether  the  benefits  from  sulfur  treatment  will  be  commensurate  with 
the  cost  on  any  alkali  soil  unless  the  drainage  conditions  are  favorable 
and  unless  the  ground  water  level  can  be  kept  down  continuously  to 
a  depth  of  six  or  more  feet  below  the  surface  of  the  soil. 

Although  excellent  crops  of  alfalfa  have  been  grown  on  several 
of  these  experimetnal   plots,   it  would   be   premature   and   certainly 


32  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

decidedly  incorrect  to  conclude  that  the  soil  has  as  yet  been  completely 
reclaimed.  The  subsoil  still  contains  an  excess  of  sodium  carbonate, 
and,  as  will  be  discussed  in  greater  detail  elsewhere,  more  thorough 
chemical  study  shows  that,  in  other  respects,  the  chemical  changes 
requisite  to  the  conversion  of  this  alkali  soil  into  normal  soil  have 
been  only  partially  brought  about.  Nevertheless,  it  seems  safe  to  say 
that  it  will  not  be  necessary  to  apply  an  additional  amount  of  any 
of  these  materials,  with  the  possible  exception  of  gypsum  in  the  case 
of  plot  11,  and  of  sulfur  in  the  case  of  plot  16,  provided,  however, 
that  careful  attention  is  given  to  the  drainage  conditions  and  to  the 
general  management  and  irrigation  of  the  soil. 

As  was  pointed  out  above,  the  changes  required  to  convert  this 
soil  into  a  state  of  normality  necessitate  the  transformation  of  the 
clay  constituents  into  calcium  compounds.  Thus  far  this  change  in 
the  treated  plots  seems  to  have  taken  place  to  the  extent  of  not  more 
than  50  per  cent  of  the  theoretical  possibility.  This  chemical  effect, 
together  with  the  removal  of  the  excess  of  soluble  salts  from  the  upper 
layers,  has  greatly  improved  the  conditions  for  crop  growth,  and  the 
soil  has  been  made  reasonably  porous  and  permeable  to  water.  The 
remaining  part  of  the  chemical  transformations  can  probably  be 
brought  about  b/v  growing  deep-rooted  crops,  together  with  the  liberal 
use  of  irrigation  water  and  the  plowing  under  of  green  manures.  By 
these  means  the  native  calcium  carbonate  will  slowly  be  made  effective 
in  promoting  a  continuation  of  the  needed  chemical  changes  in  the 
soil.  The  length  of  time  required  to  complete  these  changes  cannot 
now  be  predicted.  It  seems  reasonably  certain  that  many  years  will 
be  necessary  for  their  completion.  In  the  meantime  successful  crops 
can  probably  be  grown. 

Whatever  material  is  applied,  it  will  probably  be  desirable  to 
grow  some  leguminous  crop,  especially  after  a  period  of  heavy  leach- 
ing, since  the  available  nitrate  supply  will  be  reduced  to  a  low  level. 
Nitrates  are  known  to  be  easily  leached  out  of  soil. 

It  is  of  the  utmost  importance  for  the  practical  farmer  to  realize 
that  in  the  management  and  reclamation  of  alkali  soil  under  the 
climatic  conditions  of  California  and  other  southwestern  states,  the 
abundant  use  of  irrigation  water  is  very  desirable.  It  is  well  known 
that  black-alkali  soils  absorb  water  very  slowly,  and  unless  they  are 
irrigated  at  frequent  intervals  the  crop  will  suffer  because  of  excessive 
salt  concentration  and  may  even  perish  before  it  has  time  to  become 
established.  This  is  especially  important  in  the  early  stages  of  the 
growth  of  alfalfa.  In  our  experimental  work  we  have  found  it  neces- 
sary to  irrigate  young  alfalfa  about  once  every  two  weeks  throughout 


BUL.45.1J  RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL  33 

the  greater  part  of  the  first  season.  During  the  second  year  the 
irrigation  in  hot  weather  has  been  approximately  once  every  three 
weeks.  Moreover,  it  is  important  to  apply  the  water  in  excess  of  the 
requirements  of  the  crop  in  order  to  affect  the  subsoil  favorably,  but 
this  should  be  done  in  such  a  way  as  to  prevent  injury  to  the  crop. 
11  is  only  as  a  result  of  the  deep  penetration  of  water  applied  to  the 
surface  that  the  effects  of  artificial  treatments  can  be  carried  deep 
into  the  subsoil.  The  objective  should  be  to  transform  the  soil  to  a 
depth  of  at  least  four  feet  and  possibly  deeper,  and  the  needed 
changes  in  the  subsoil  cannot  be  brought  about  quickly  with  the  use 
of  sulfur  or  any  other  material  except  at  prohibitive  cost. 

While  these  plots  have  not  as  yet  been  completely  reclaimed,  there 
is  good  reason  to  believe  that  the  conditions  for  crop  growth  will 
continue  to  improve,  provided  the  ground  water  is  kept  down  below 
the  zone  of  root  development.  In  this  connection  it  should  be  clearly 
understood  that  soluble  salts  are  the  cause  either  directly  or  indirectly 
of  the  adverse  conditions  of  all  alkali  soils.  Once  the  salts  have  been 
removed  there  is  no  possibility  of  their  return  unless  the  ground  water 
approaches  the  surface,  or  unless  saline  irrigation  water  is  applied. 
If  the  water  table  is  not  kept  down,  it  is  certain  that  the  beneficial 
effects  of  the  treatments  will  be  merely  temporary. 

Finally,  we  believe  that  the  successful  outcome  of  these  reclama- 
tion experiments  has  not  been  due  solely  to  the  fact  that  good  drainage 
conditions  were  established  and  the  right  kind  of  materials  have  been 
applied.  The  care  that  has  been  given  to  the  details  of  soil  prepara- 
tion and  irrigation  have  probably  also  played  an  important  part  in 
the  results.  Before  the  various  materials  were  applied  the  soil  was 
carefully  leveled  so  that  each  check  could  be  irrigated  uniformly. 
Subsequently  it  was  necessary  to  relevel  the  soil  from  time  to  time 
owing  to  inequalities  that  developed  in  consequence  of  settling  or 
plowing. 

It  is  especially  important  to  provide  a  good  seed  bed  and  suitable 
moisture  conditions  before  sowing  alfalfa.  If  the  soil  is  too  dry,  it 
may  be  necessary  to  irrigate  before  the  seed  will  germinate,  and,  as 
is  well  known,  this  should  be  avoided  on  any  soil ;  its  avoidance  is  even 
more  important  with  alkali  soils  because  of  their  pronounced  tendency 
to  bake.  We  have  secured  equally  good  results  from  seeding  in 
October  and  February,  but  in  neither  case  was  it  necessary  to  irrigate 
before  the  alfalfa  seed  germinated.  As  stated  already,  light  irriga- 
tions were  applied  at  approximately  two-week  intervals  during  the 
first  summer  after  alfalfa  was  sown.  Subsequently  water  has  been 
applied  freely  and  at  intervals  of  approximately  three  weeks. 


34  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


SUMMARY 

1.  Field  experiments  on  Section  6  of  the  Kearney  Vineyard  have 
shown  that  the  crop-producing  power  of  the  Fresno  black-alkali  soil 
can  be  greatly  improved  by  the  use  of  gypsum,  sulfur,  iron  sulfate, 
or  alum,  provided  these  materials  are  applied  in  sufficient  amounts. 
Yields  of  alfalfa  ranging  from  6  to  11  tons  per  acre  per  annum  have 
been  produced  on  land  which  at  the  beginning  of  the  experiments 
was  entirely  unproductive. 

2.  The  unproductivity  of  this  soil  is  due  to  (a)  an  excess  of  soluble 
salts,  especially  sodium  carbonate,  and  (&)  the  abnormal  chemical 
composition  of  the  clay-like  constituents  of  the  soil.  The  reclamation 
of  the  soil  must  involve  the  removal  of  the  excess  of  soluble  salts  and 
the  conversion  of  at  least  a  part  of  the  clay  constituents  into  calcium 
compounds.  The  former  may  be  leached  out,  but  ordinary  leaching 
fails  to  bring  about  the  needed  chemical  changes  in  the  latter. 

3.  Gypsum,  sulfur,  iron  sulfate,  and  alum  produce  beneficial 
effects  on  black-alkali  soils  but  at  different  rates.  These  materials 
act  on  the  soluble  carbonate  and  the  clay  constituents  simultaneously. 
Gypsum  brings  about  these  changes  because  of  its  soluble  calcium, 
while  the  effect  of  sulfur,  iron  sulfate,  and  alum  is  due  to  their  acidic 
nature,  in  consequence  of  which  soluble  carbonate  is  decomposed  and 
calcium  minerals  of  the  soil,  especially  calcium  carbonate,  are  dis- 
solved. The  calcium  thus  brought  into  solution  reacts  with  the  clay 
constituents.  Iron  sulfate  and  alum  react  with  the  soil  most  quickly 
because  of  their  high  solubility  and  acidic  nature.  Sulfur  acts  most 
slowly  for  the  reason  that  this  material  must  undergo  oxidation 
before  it  can  produce  any  important  effect  on  the  soil. 

4.  Gypsum  produced  uniformly  successful  results  on  this  soil  only 
when  applied  at  the  rate  of  more  than  10  tons  per  acre.  Relatively 
large  amounts  of  iron  sulfate  and  alum  are  also  required.  On  the 
other  hand,  excellent  results  have  been  obtained  by  applying  not  more 
than  one  ton  of  sulfur  per  acre. 

5.  Sulfur  has  proven  to  be  much  more  economical  than  the  other 
materials.  Large  yields  of  alfalfa  have  been  produced  on  soil  that 
was  badly  affected  with  alkali  and  entirely  unproductive  at  the  outset 
by  applying  one  ton  of  sulfur  per  acre;  when  used  in  conjunction 
with  stable  manure,  1000  pounds  of  sulfur  per  acre  has  given  good 
results. 


BUL.  455]         RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL  35 

6.  It  seems  safe  to  say  that  where  the  natural  drainage  conditions 
are  satisfactory  the  Fresno  black-alkali  soil  similar  to  that  on  the 
Kearney  Vineyard  can  be  reclaimed  with  sulfur  at  an  average  cost 
for  the  material  itself  of  not  more  than  $45.00  an  acre.  By  combin- 
ing the  use  of  sulfur  with  farm  manures  or  the  growing  of  alkali- 
resistant  leguminous  cover  crops,  it  is  probable  that  the  cost  will 
be  somewhat  less.  This  estimate  is  based  on  the  current  quotation 
of  $45.00  a  ton  for  practically  pure,  finely  ground  sulfur.  Should  it 
be  found  that  some  one  or  more  of  the  less  expensive  forms  of  crude 
sulfur  concentrates  are  effective,  and  it  seems  probable  that  such  will 
be  the  case,  then  the  cost  would  be  materially  reduced. 

7.  Since  the  Fresno  black-alkali  soil  is  extremely  variable  as 
regards  the  alkali  conditions,  we  would  recommend  that  sulfur  be 
applied  at  the  rate  of  1000  pounds  per  acre.  If  after  the  lapse  of 
two  or  more  years,  the  growth  of  alfalfa  or  other  crops  should  indicate 
the  need  for  further  treatment,  an  additional  application  should  be 
made  in  accordance  with  that  indication.  It  wrill  probably  not  be 
necessary  to  make  a  second  application  except  on  scattered  spots. 
By  following  this  plan  the  average  cost  for  materials  will  probably 
be  considerably  less  than  $45.00  an  acre. 

8.  Leaching  experiments  without  the  application  of  any  material 
except  water  have  thus  far  failed  to  bring  about  a  satisfactory  recla- 
mation of  this  soil. 

9.  Although  the  beneficial  effect  of  sulfur  is  dependent  on 
oxidation,  and  the  oxidation  is  brought  about  by  certain  species  of 
bacteria,  these  experiments  have  not  shown  any  special  advantage  for 
artificially  inoculated  sulfur  over  that  obtained  from  uninoculated 
sulfur.  Active  forms  of  one  or  more  of  the  species  of  sulfur-oxidizing 
bacteria  occur  naturally  in  this  soil  and  nothing  appears  to  be  gained 
by  special  inoculation  of  the  sulfur. 

10.  It  is  important  for  the  farmer  to  realize  that  several  months 
and  possibly  a  year  or  more  must  elapse  after  the  sulfur  is  applied 
before  the  full  effect  will  be  exerted.  During  this  period  the  soil 
should  be  kept  moist  and  well  tilled  in  order  to  promote  aeration  and 
hasten  the  rate  of  sulfur  oxidation.  It  is  probably  best  not  to  leach 
the  soil  during  this  stage  of  the  work.  If  the  content  of  soluble  salts 
is  high,  the  soil  should  be  flooded  prior  to  the  time  of  planting  a  crop 
in  order  to  leach  out  the  excess  of  salts.  If,  on  the  other  hand,  the 
salt  content  is  not  especially  high,  water  applied  rather  freely  to  the 
crops  that  are  grown  by  the  flooding  system  of  irrigation  will  probably 
suffice  to  leach  out  the  salts  and  wash  down  the  sulfur-oxidation 
products  and  thus  gradually  ameliorate  the  subsoil. 


36  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

11.  It  is  extremely  important  to  irrigate  young  alfalfa  on  alkali 
soil  at  frequent  intervals.  In  fact,  success  in  the  growth  of  crops 
during  the  early  stages  of  the  reclamation  will  probably  depend 
largely  on  careful  attention  to  the  irrigation  program,  and  especially 
so  during  the  time  when  young  alfalfa  is  becoming  established.  We 
have  found  it  desirable  to  irrigate  about  twice  a  month  during  the 
first  summer  after  alfalfa  was  planted.  Alkali  soil  should  never  be 
allowed  to  dry  out  while  crops  are  being  grown,  and  success  in  alkali 
reclamation  will  depend  to  an  unusual  degree  upon  careful  attention 
to  the  details  of  soil  preparation  and  irrigation.  Alkali  soils  are 
much  more  difficult  to  manage  successfully  than  normal  soils. 

12.  Unless  the  soil  is  well  drained  there  is  no  reasonable  prospect 
of  permanently  reclaiming  any  alkali  soil.  We  believe  that  under 
the  soil  and  climatic  conditions  that  prevail  in  the  Fresno  section,  the 
water  table  should  never  be  less  than  6  feet  below  the  surface,  and 
preferably  deeper.  Since  1924  the  minimum  depth  to  the  ground 
water  on  the  experimental  area  at  Kearney  Park  has  been  about  8 
feet,  and  during  a  large  part  of  each  year  it  has  been  12  feet  or  more. 
The  ground  water  has  been  kept  down  not  by  the  tile-drainage  system, 
but  by  pumping  from  a  deep  well  located  near  the  experimental  area. 
This  water  is  used  on  the  experimental  plot  as  the  sole  source  of 
irrigation  supply.  When  not  needed  for  this  purpose  it  is  discharged 
into  a  near-by  canal.  The  pump  is  kept  in  continuous  operation  about 
eight  months  each  year. 

13.  The  first  foot  of  soil  has  been  practically  freed  from  soluble 
carbonate  as  a  result  of  applying  gypsum,  sulfur,  iron  sulfate,  or 
alum,  and  the  second  foot  has  been  materially  improved.  The  third 
and  fourth  feet  of  certain  plots  have  also  been  affected.  Nevertheless, 
none  of  the  plots  can  yet  be  said  to  be  completely  reclaimed.  It  is 
probable,  however,  that  by  giving  careful  attention  to  the  drainage, 
irrigation,  and  general  management  of  the  soil,  the  conditions  will 
continue  to  improve,  and  that  ultimately  this  soil  will  be  completely 
restored  to  a  condition  of  normality. 


BuL.  455]         RECLAMATION  OF  FRESNO  TYPE  OF  BLACK  ALKALI  SOIL  37 


LITERATURE   CITED 

i  Kelley,  W.  P.,  and  Alexander  Arany. 

.     The   chemical   effect   of   gypsum,   sulfur,   iron    sulfate,   and    alum    on 

alkali  soil.     Hilgardia.      (In  press.) 

a  Kelley,  Walter  P.,  and  Edward  E.  Thomas. 

1923.     The  removal  of  sodium  carbonate  from  soils.     California  Agr.  Exp. 
Sta.  Tech.  Paper  1:1-24. 

8  Samuels,  Charles  Danziger. 

1927.     The  oxidation  of  sulfur  in  alkali  soil  and  its  effect  on  the  replaceable 
bases.     Hilgardia  3:1-26. 

4  Weir,  Walter  W. 

1916.     Preliminary  report  on  Kearney  Vineyard  experimental  drain.     Cali- 
fornia Agr.  Exp.  Sta.  Bui.  273:103-123. 

s  Weir,  Walter  W. 

1927.     Effect  of  pumping  from  deep  wells  on  the  ground-water  table.     Jour. 
Agr.  Research  34:663-672.  ' 


STATION  PUBLICATIONS  AVAILABLE  FOR  FREE   DISTRIBUTION 


BULLETINS 


No.  No. 

253.  Irrigation   and   Soil  Conditions  in  the  386. 

Sierra    Nevada   Foothills,    California. 

262.  Citrus   Diseases   of   Florida   and   Cuba  387. 

Compared  with   those  of   California.  388. 

263.  Size  Grades  for  Ripe  Olives. 

268.  Growing  and  Grafting  Olive  Seedlings.  389. 

273.  Preliminary  Report  on  Kearney  Vine-  390. 

yard     Experimental     Drain,     Fresno 
County,    Calif.  391. 

277.  Sudan  Grass. 

278.  Grain  Sorghums.  392. 

279.  Irrigation  of  Rice  in  California.  393. 
283.  The  Olive  Insects  of  California.  394. 
304.  A  Study  of  the  Effects  of  Freezes  on 

Citrus  in  California. 

310.   Plum  Pollination.  395. 

313.   Pruning      Young      Deciduous      Fruit 

Trees.  396. 

324.   Storage  of  Perishable  Fruits  at  Freez- 
ing Temperatures.  397. 

328.   Prune   Growing  in   California. 

331.   Phylloxera-resistant  Stocks.  398. 

335.   Cocoanut   Meal    as   a    Feed    for    Dairy  400. 

Cows   and   Other   Livestock.  402. 

340.  Control     of     the     Pocket     Gopher     in  404. 

California.  405. 

343.  Cheese   Pests  and  Their  Control.  406. 

344.  Cold    Storage   as   an   Aid   to   the   Mar-  407. 

keting  of  Plums,  a  Progress  Report. 

347.  The  Control  of  Red  Spiders  in  Decid- 

uous Orchards,  408. 

348.  Pruning  Young  Olive  Trees.  409. 

349.  A    Study    of    Sidedraft    and    Tractor 

Hitches. 

350.  Agriculture      in      Cut-Over      Redwood 

Lands.  410. 

353,  Bovine    Infectious    Abortion,    and    As- 

sociated Diseases  of  Cattle  and  New- 
born Calves.  411. 

354.  Results  of  Rice  Experiments  in  1922. 

357.  A    Self-Mixing    Dusting    Machine    for  412. 

Applying  Dry  Insecticides  and  Fun- 
gicides. 

358.  Black    Measles,    Water    Berries,    and  414. 

Related  Vine  Troubles. 

361.  Preliminary  Yield  Tables  for   Second-  415. 

Growth   Redwood.  416. 

362.  Dust  and  the  Tractor  Engine. 

363.  The  Pruning  of  Citrus  Trees  in  Cali-  417. 

fornia. 

364.  Fungicidal    Dusts    for    the    Control    of  418. 

Bunt. 

366.  Turkish     Tobacco     Culture,     Curing,  419. 

and  Marketing. 

367.  Methods  of  Harvesting  and  Irrigation  420. 

in  Relation  to  Moldy  Walnuts. 

368.  Bacterial      Decomposition     of      Olives  421. 

During   Pickling.  422. 

369.  Comparison     of     Woods     for     Butter 

Boxes.  423. 

370.  Factors    Influencing   the    Development 

of  Internal  Browning  of  the  Yellow  424. 

Newton   Apple. 

371.  The    Relative    Cost   of   Yarding    Small  425. 

and  Large  Timber.  426. 

373.  Pear   Pollination. 

374.  A    Survey    of    Orchard    Practices    in  427, 

the     Citrus     Industry     of     Southern 
California.  428. 

375.  Results   of    Rice   Experiments   at   Cor- 

tena,  1923,  and  Progress  in  Experi- 
ments in  Water  Grass  Control  at  the  429. 
Biggs   Rice   Field    Station,    1922-23.  430. 
377.  The  Cold  Storage  of  Pears.  431. 

379.  Walnut   Culture   in    California. 

380.  Growth    of    Eucalyptus    in    California  432. 

Plantations. 
382.   Pumping    for    Draininge    in    the    San  433. 

Joaquin   Valley,    California. 
385.  Pollination  of  the  Sweet  Cherry. 


Pruning  Bearing  Deciduous  Fruit 
Trees. 

Fig   Smut. 

The  Principles  and  Practice  of  Sun- 
Drying  Fruit. 

Berseem  or  Egyptian  Clover. 

Harvesting  and  Packing  Grapes  in 
California. 

Machines  for  Coating  Seed  Wheat 
with   Copper   Carbonate   Dust. 

Fruit  Juice  Concentrates. 

Crop   Sequences  at  Davis. 

I.  Cereal  Hay  Production  in  Cali- 
fornia. II.  Feeding  Trials  with 
Cereal  Hays. 

Bark  Diseases  of  Citrus  Trees  in  Cali- 
fornia. 

The  Mat  Bean,  Phaseolus  Aconitifo- 
lius. 

Manufacture  of  Roquefort  Type  Cheese 
from  Goat's  Milk. 

Orchard    Heating  in   California. 

The  Utilization  of  Surplus  Plums. 

The  Codling  Moth  in  Walnuts. 

The  Dehydration  of  Prunes. 

Citrus   Culture   in    Central    California. 

Stationary  Spray  Plants  in  California. 

Yield,  Stand,  and  Volume  Tables  for 
White  Fir  in  the  California  Pine 
Region. 

Alternaria  Rot  of  Lemons. 

The  Digestibility  of  Certain  Fruit  By- 
products as  Determined  for  Rumi- 
nants. Part  I.  Dried  Orange  Pulp 
and  Raisin  Pulp. 

Factors  Influencing  the  Quality  of 
Fresh  Asparagus  after  it  is  Har- 
vested. 

Paradichlorobenzene  as  a  Soil  Fumi- 
gant. 

A  Study  of  the  Relative  Value  of  Cer- 
tain Root  Crops  and  Salmon  Oil  as 
Sources   of   Vitamin   A  for   Poultry. 

Planting  and  Thinning  Distances  for 
Deciduous  Fruit  Trees. 

The  Tractor  on   California  Farms. 

Culture  of  the  Oriental  Persimmon  in 
California. 

Poultry  Feeding:  Principles  and  Prac- 
tice. 

A  Study  of  Various  Rations  for  Fin- 
ishing Range  Calves    as  Baby  Beeves. 

Economic  Aspects  of  the  Cantaloupe 
Industry. 

Rice  and  Rice  By-Products  as  Feeds 
for  Fattening  Swine. 

Beef   Cattle  Feeding  Trials,    1921-24. 

Cost  of  Producing  Almonds  in  Cali- 
fornia :  a  Progress  Report. 

Apricots  (Series  on  California  Crops 
and   Prices). 

The  Relation  of  Rate  of  Maturity  to 
Egg  Production. 

Apple  Growing  in  California. 

Apple  Pollination  Studies  in  Cali- 
fornia. 

The  Value  of  Orange  Pulp  for  Milk 
Production. 

The  Relation  of  Maturity  of  Cali- 
fornia Plums  to  Shipping  and 
Dessert  Quality. 

Economic  Status  of  the  Grape  Industry. 

Range  Grasses  of  California. 

Raisin  By-Products  and  Bean  Screen- 
ings as  Feeds  for  Fattening  Lambs. 

Some  Economic  Problems  Involved  in 
the  Pooling  of  Fruit. 

Power  Requirements  of  Electrically 
Driven    Manufacturing    Equipment. 


No. 

434.  Investigations  on  the  Use  of  Fruits  in 

Ice  Cream  and  Ices. 

435.  The      Problem      of      Securing      Closer 

Relationship  Between  Agricultural 
Development  and  Irrigation  Con- 
struction. 

436.  I.   The  Kadota   Fig.     II.   Kadota   Fig 

Products. 

437.  Economic    Aspects    of    the    Dairy    In- 

dustry. 

438.  Grafting  Affinities  with  Special  Refer- 

ence to  Plums. 

439.  The  Digestibility  of  Certain  Fruit  By- 

products as  Determined  for  Rumi- 
nants. Part  II.  Dried  Pineapple 
Pulp,  Dried  Lemon  Pulp,  and  Dried 
Olive  Pulp. 


BULLETINS—  (Continued) 
No. 

440.  The  Feeding  Value  of  Raisins  and 
Dairy  By-Products  for  Growing  and 
Fattening  Swine. 

441.  The  Electric  Brooder. 

442.  Laboratory  Tests  of  Orchard  Heaters. 

443.  Standardization  and  Improvement  of 
California   Butter. 

444.  Series  on  California  Crops  and  Prices: 
Beans. 

445.  Economic  Aspects  of  the  Apple  In- 
dustry. 


CIRCULARS 
No. 
257. 


No. 

87.  Alfalfa. 
115.   Grafting  Vinifera  Vineyards. 

117.  The    selection    and    Cost    of    a    Small  258. 

Pumping  Plant.  259. 

127.   House  Fumigation.  261. 

129.  The  control  of  Citrus  Insects.  264. 
136.  Melilotus    Indica    as    a    Green-Manure 

Crop  for  California.  265. 

144.   Oidium    or    Powdery    Mildew    of    the  266. 

Vine. 

157.  Control  of   Pear   Scab.  267. 
164.    Small   Fruit   Culture   in    California. 

166.  The  County  Farm  Bureau.  269. 

173.  The    Construction    of    the    Wood-Hoop  270. 

Silo.  273. 

178.  The  Packing  of  Apples  in'  California.  276. 

179.  Factors    of    Importance    in    Producing  277. 

Milk  of  Low  Bacterial  Count. 

202.  County    Organization    for    Rural    Fire  278. 

Control. 

203.  Peat  as   a  Manure   Substitute.  279. 
209.  The  Function  of  the  Farm  Bureau. 
212.   Salvaging  Rain-Damaged  Prunes.  281. 
215.  Feeding  Dairy   Cows  in   California. 
217.  Methods   for   Marketing  Vegetables  in 

California.  282. 

230.  Testing  Milk,    Cream,    and   Skim  Milk 

for  Butterfat.  283. 

231.  The  Home  Vineyard.  284. 

232.  Harvesting    and    Handling    California  286. 

Cherries   for   Eastern    Shipment.  287. 

234.  Winter     Injury     to     Young     Walnut  288. 

Trees  During  1921-1922.  289. 

238.  The   Apricot  in   California.  290. 

239.  Harvesting     and     Handling     Apricots  292. 

and  Plums  for  Eastern  Shipment.  293. 

240.  Harvesting    and    Handling    California  294. 

Pears  for  Eastern  Shipment.  296. 

241.  Harvesting    and    Handling    California 

Peaches  for  Eastern   Shipment.  298. 

243.  Marmalade     Juice     and     Jelly     Juice 

from  Citrus  Fruits.  300. 

244.  Central  Wire  Bracing  for  Fruit  Trees.  301. 

245.  Vine  Pruning   Systems.  302. 

248.  Some  Common   Errors  in  Vine  Prun-  304. 

ing  and  Their  Remedies.  305. 

249.  Replacing  Missing  Vines.  306. 

250.  Measurement  of   Irrigation   Water   on 

the  Farm.  '307. 

252.  Support   for   Vines.  308. 

253.  Vineyard   Plans.  309. 

254.  The    Use    of    Artificial    Light    to    In-  310. 

crease  Winter  Egg  Production. 

255.  Leguminous    Plants    as    Organic    Per-  311. 

tilizers  in   California   Agriculture. 

The  publications  listed  above  may  be  had  by  addressing 

College  of  Agriculture, 

University  of  California, 

Berkeley,  California. 

16to-6,'28 


The  Small-Seeded  Horse  Bean  (Vicia 
faba   var.   minor). 

Thinning   Deciduous   Fruits. 

Pear  By-Products. 

Sewing  Grain  Sacks. 

Preliminary  Essentials  to  Bovine  Tu- 
berculosis Control  in   California. 

Plant   Disease  and   Pest  Control. 

Analyzing  the  Citrus  Orchard  by 
Means  of  Simple  Tree  Records. 

The  Tendency  of  Tractors  to  Rise  in 
Front;  Causes  and  Remedies. 

An   Orchard   Brush   Burner. 

A  Farm  Septic  Tank. 

Saving  the  Gophered  Citrus  Tree. 

Home   Canning. 

Head,  Cane  and  Cordon  Pruning  of 
Vines. 

Olive  Pickling  in  Mediterranean 
Countries. 

The  Preparation  and  Refining  of 
Olive  Oil  in  Southern  Europe. 

The  Results  of  a  Survey  to  Deter- 
mine the  Cost  of  Producing  Beef  in 
California. 

Prevention  of  Insect  Attack  on  Stored 
Grain. 

Fertilizing  Citrus  Trees  in  California. 

The  Almond  in   California. 

Milk  Houses  for  California  Dairies. 

Potato   Production  in   California. 

Phylloxera  Resistant  Vineyards. 

Oak  Fungus  in   Orchard  Trees. 

The  Tangier  Pea. 

Alkali   Soils. 

The    Basis   of   Grape    Standardization. 

Propagation   of   Deciduous  Fruits. 

Control  of  the  California  Ground 
Squirrel. 

Possibilities  and  Limitations  of  Coop- 
erative Marketing. 

Coccidiosis  of  Chickens. 

Buckeye  Poisoning  of  the  Honey  Bee. 

The   Sugar  Beet  in  California. 

Drainage  on  the  Farm. 

Liming  the   Soil. 

A  General  Purpose  Soil  Auger  and 
Its  Use  on  the  Farm. 

American  Foulbrood   and  Its  Control 

Cantaloupe    Production    in    California. 

Fruit  Tree  and   Orchard  Judging. 

The  Operation  of  the  Bacteriological 
Laboratory  for  Dairy  Plants. 

The  Improvement  of   Quality  in  Figs. 


